Electronic devices each provided with a touch panel, such as smartphones and tablets have been widespread. Such electronic devices include those provided with an electrostatic-capacitance touch panel, which can accept not only “touch operation” performed by finger(s) of a bare hand directly touching the surface of the touch panel, but also “hover operation” performed by the finger at a predetermined height from the surface of the touch panel without the finger of the bare hand touching the surface of the touch panel. Accordingly, the user can perform operation not only with a bare hand but also with a hand in a glove.
FIG. 19 schematically shows an example of configuration of an electrostatic-capacitance touch panel. In FIG. 19, transmission electrode 101 and reception electrode 102 are arranged apart from each other on a lower face of plate-like dielectric body 100. A drive pulse is applied to transmission electrode 101 from drive buffer 103 to generate an electric field. When a finger enters this electric field, the number of lines of electric force between transmission electrode 101 and reception electrode 102 decreases. This change in the lines of electric force appears as a change in electrical charge in reception electrode 102. Approach of a finger to the touch panel is detected from the change in the electrical charge in reception electrode 102.
FIGS. 20A-20C show states where the fingers are detected when the fingers are gradually brought into proximity to an electrostatic-capacitance touch panel. FIG. 20A shows a state where the fingers do not enter an electric field, that is, the fingers are not detected. FIG. 20B shows a state where the fingers enter the electric field, but do not touch the touch panel, that is, hover operation is detected. FIG. 20C shows a state where the fingers enter the electric field and touch the touch panel, that is, touch operation is detected. It should be noted that operation performed by the fingers in a glove touching the touch panel corresponds to the state shown in FIG. 20B because the fingers do not directly touch the touch panel.
As the related art relating to such an electrostatic-capacitance touch panel, for example, Japanese Patent Application Laid-Open No. 2011-53971 (hereinafter, referred to as “PTL 1”) discloses an information processing apparatus (hereinafter, referred to as “related art 1”). Related art 1 is an information processing apparatus configured to detect a degree of proximity of the fingers with respect to the touch panel and a value of pressure applied to the touch panel and to distinguish between touch operation and hover operation according to whether or not the degree of proximity and the value of pressure satisfy predetermined conditions.
Further, as another related art relating to the electrostatic-capacitance touch panel, for example, Japanese Patent Application Laid-Open No. 2009-181232 (hereinafter, referred to as “PTL 2”) discloses a touch switch (hereinafter, referred to as “related art 2”). The touch switch according to related art 2 is configured to determine that “there is touch operation” when a detection value in the touch panel exceeds a first threshold and to determine that “there is hover operation” when a predetermined time period elapses in a state where the detection value in the touch panel is equal to or less than the first threshold but exceeds a second threshold.